Variable stroke cushioned valves



3 Sheets-Sheet 1 Original Filed July 28, 1948 lnnentor DAVID W HOPKINS.

III h i Sept. 4, 1956 D. w. HOPKINS 2,761,424

VARIABLE STROKE CUSHIONED VALVES Original Filed Jul 28, 1948 :5Shets-Sheet 2 lnneutor DAVID W. HOPKINS- Ottoman;

p 4, 1956 D. w. HOPKINS 2,761,424

VARIABLE STROKE CUSHIONED VALVES Original Filed July 28, 1948 I5Sheets-Sheet 3 5 H I! I! L ll/ l J I 14 a i Zinnentor DA v/o w. HOPKINS.

// attorney Patented Sept. 4:, 1953 nice 2,761,424 VARIABLE STROKECUSHIONED VALVES David Walter Hopkins, Philadelphia, Pa., assignor to11-5 Products Corporation, Philadelphia, Pa., a corporation ofPennsylvania Original application July 28, 1948, Serial No. 41,028, nowPatenhNo. 2,646,074, dated July 21, 1953. Divided and this applicationApril 30, 1953, Serial No. 352,253

2 Claims. (Cl. 121-38) This invention relates to cushioned variablestroke valves and is a division of Patent 2,646,074, eventuating fromapplication 41,028, filed July 28, 1948.

It has been found essential for the long life of valves, in those caseswhere the valve actuation is as a result of the stroke of a power pistoncoupled to the movable portion of the valve, and particularly, althoughnot restrictedly, to vanes of butterfly valves, that both the closingand the opening strokes must be retarded and cushioned just prior toattainment of the particular limit of the valve element motion. Manydevices have been proposed for the purpose.

A cushioned stroke of the power piston and cylinder in effect provides asort of dash pot at the ends of the stroke, by which entrapped fluid,such as air, is compressed and slowly allowed to bleed to permit thecompletion of the stroke. This is quite satisfactory, but it isrestricted in operativeness, as far as the cushioning of the stroke inboth directions is concerned at least, to the full stroke of the valve,between fully open and fully closed, or requires changes in leverage inorder to modify the actual valve movement, which is a complex matterinvolving replacement of parts. As there are many situations in which apartial stroke only is desired, known existing equipment as it isprovided is powerless to secure such cushioned partial stroke.

It is among the objects of this invention to provide a power cylinderfor operating valves having a variable stroke which is cushioned at bothends thereof; to improve valve actuating devices; to provide a valveactuating device having one fixed cushioned limit to its stroke andhaving the other limit a variable to limit the length of the effectivestroke with means for cushioning the stroke at such variable limit; toimprove valve constructions; to provide a variable stroke valveoperating assembly with cushioning at each end of the stroke, in whichthe variation is a simple, easy, and quick manual actuation; and toprovide other objects and improvements as will hereinafter appear.

In the accompanying drawings forming part of this description:

Fig. 1 represents a side elevation, partially in fragmentary section,through a valve-operating mechanism provided with a stroke adjustmentcushioning device, showing the adjustment of the latter to permit thefull power stroke of the actuating device;

Fig. 2 represents a fragmentary side elevation, partially in fragmentarysection, of the stroke adjustment cushioning device in a position ofadjustment for securing a substantially half stroke only from the powerunit shown in Fig. 1;

Fig. 3 represents a side elevation of the device of Fig. 1, with theparts in the position shown in Fig. 1;

Fig. 4 represents a fragmentary side elevation, partially in verticalsection, through a modified form of the invention, in which theadjustment is in the power cylinder itself;

Fig. 5 represents a fragmentary side elevation, partially in verticalsection of the power cylinder showing an adjustment thereof to establishsubstantially one-half stroke from the mechanism.

The valve body It is provided with attaching flanges ii and with amovable element for closing and openthe valve. lllustratively, butpreferably, the valve in question is a butterfly valve controlled by avane 12 mounted on a suitable shaft, passing outwardly through astufling box or the like 13. A worm gear 14 is mounted fordisconnectible engagement with the shaft of the vane 1.2, controlledfrom the outer end of the assembly by the axially movable push element15 mounted on the push rod 16. This portion of the assembly is of noimportance so far as this invention is concerned, and the worm gear iskeyed to or released from the vane shaft as the element 15 is pushed inor out, in any desired manner. A hand wheel 17 is provided on a shaft 18in driven relation to a worm pinion gear 20 in constant mesh with theworm gear 14. This is to permit hand operation of the vane when desiredor necessary. A lever 21 is mounted on the shaft of the vane 12, and hasa power operated arm 22 and a damping or restraining arm 23, insubstantial alignment across the axis of the shaft of the vane. Theusually longer arm 22, at its free end carries pivotally one end of anadjustable link 24, and the other end of the link 24 is pivoted to theend of the power shaft or piston rod 25 connected to the piston 26 ofthe power cylinder 27. The power cylinder 27 may be formed as desired solong as it provides cushioning at one end of the stroke at least. In theposition of the parts shown in full lines in Fig. 1, the piston 26 is atthe upper end of its stroke. Suitable compression space defining meansare provided to insure that entrapped fluid is compressed and vented atthe top in any desired manner as shown, for instance, in section at thebottom of the cylinder. The upper and lower closures of the cylinder aresubstantially identical (except for the passage of shaft or connectingrod 25), and the stroke is cushioned at both ends thereof, so that noadditional disclosure of the upper end is deemed necessary. The cylinderend is provided with a transverse barrier-surface 28, against which thepiston compresses air or other fluid. It will be understood that thecushion may be pre-set by providing a fixed rate of bleed as shown inFigs. 4 and 5, or may be made adjustable as will be described of thedisclosure of Fig. 1. The compressed fluid passes through small orifice30 into the chamber 31 restricted in its flow by the adjustable needlevalve 29, and passes at a controlled rate into chamber 31, from which bya vent aperture 9 it passes out of the chamber 31. This is facilitatedby the axial sealing projection 32 on the piston 26, which extends intoand seals the axially extending orifice 33 forming a communicationbetween the annular chamber 31 and the cylinder bore. At this time theball check valve 34 is closed by its spring 35 and the cushioning is ata rate controlled by the needle valve. To apply working pressure to thepiston, fluid under pressure is brought into the vent orifice at suchpressure as to unseat the ball check valve,.to free passage through port36 against the end of the piston in the cylinder. If any fluid underpressure passes through the needle valve aperture, it, too, passes intothe cylinder against the piston.

With the power piston so furnished, it will be seen that the stroke ofthe shaft 25 through a full stroke is cushioned at each end of thestroke, and that starting with the valve full open (in full lines), forinstance, it will be forced to full closed (in the dotted line positionindicated). In this stroke the stop element 40 carried by the shaft ofthe vane of the valve will move from its abutment against the adjustablestop 41 carried by the valve housing or stufiing box, from the positionshown in full lines in Fig. l, to the dotted line position, with theabutment 4t) engaged against the adjustable limit stop 42, a duplicatein reverse of the stop 41. Of course, for such power actuation, the wormgear 14 will be released from its keyed connection to the shaft of thevane. The cushioning prevents the sharp impact of the mechanism at theend of the stroke and is quite desirable. As noted, if a full strokealone is desired, nothing more need be provided than has just beendescribed. However, in order to provide a shorter stroke for any reason,and the reasons are frequent, it will be seen. that the cushioned powerdevice illustrated is inefiective. It is, therefore, preferred toprovide a variable cushion device as shown, for instance, at the righthand side of Fig. I. In this illustrative disclosure, an internallythreaded bushing 43 is provided upon a fixed portion 44 of the housing,upon which the power cylinder 27 is mounted. A cushion cylinder 45 isexternally threaded and screwed into the bushing 43, and carries a handwheel 46, by which the vertical axial position of the cylinder 45 can bevaried by rotating the cylinder. The cylinder has an internal abutment47 provided with an air inlet and exhaust opening 48', if desired,although the cylinder may just be formed with an open end. The cylinder45 has an outer flange 49 for abutment and stop against the upper end ofthe bushing to mark the limit of downward adjustment of the cylinder,and is provided with the radial vent openings 50 in spaced relation tothe end of the inserted plug 51. The plug has an axial bore 52, the flowthrough which is controlled by the needle valve 53, and the bore 52 isin communication with an exhaust passage 54. A piston rod 55 is provided with a piston 56, which latter is slidable with the shaft or rod55 axially of the cylinder. The lower end of the shaft 55 is pivoted atone end of the link 57 and the latter pivots to the lever arm 23. Itwill be seen that as the power cylinder functions and the piston isforcedto the bottom of its stroke in cylinder 27, the arm 22 is forceddownwardly, thus rotating or moving the valve element of the valve inone direction. At the same time the lever arm 23 is elevated movingabout the axis of the shaft on the vane or other moving device of thevalve,

forcing the piston 56 of the cushion cylinder upwardly, x

more or less slightly compressing the air therein as it goes. Most ofthe air being compressed escapes through the side vents 50 of thecylinder, but when the piston has passed by these the escape of air isprecluded and it is then that actual working or cushioning compressionof the air begins. The piston is sharply decelerated then in itsmovement as the air escapes ahead of. it through port 52 controlled inbleed rate by the needle valve 53, to final escape through the exhaustport. As a general proposition, to reduce the drag on the power cylinderwith the cushioning of the stroke at each end is being used for its fullstroke, the auxiliary cushioning device will have the needle valve movedto its full opening to expedite escape of the entrapped air.

When it is desired to provide a limited stroke to the valve movableelement, say, for instance, in a purely illustrative form, a strokebetween closed and one-half open, the valve is moved by hand orotherwise until it is in the half way position. Then the hand wheel 46is turned and the cylinder 45 is screwed into the bushing to move thecylinder axially downwardly until the end of the piston 56 engages andabuts against the plug 51. Then the needle valve is partially closed toestablish the desired slow bleed rate and the mechanism is started. Thepower cylinder being operated causes the piston to move partiallydownwardly on its stroke to move the valve movable element from its onelimit toward the arbitrarily set limit, and the piston 56 moves part wayon its complete stroke in the cylinder 45. The substantially closed endof the cushioning cylinder has now been moved partially downwardlyelement, when the power toward the piston 56 so that as the valvemovable element moves toward the new limit, i. e. the illustrative halfway position, the piston passes by the escape vents and starts to slowdown as the entrapped air compresses ahead of it. As the latter slowlybleeds out, the piston 56 gently abuts and is positively stopped againstthe plug 51 and the valve movement stops at the desired point and with acushioning of the stop. On. the return stroke the fluid pressure movesthe power piston 26 upwardly toward its cushioned stop at the same timethat the piston 56 is withdrawn from adjacency to the plug 51, drawingin air partially through the bleed ports and then fully through theradial openings 56, to recharge the cushion cylinder with air, withouteffecting any su' tantial drag on the power cylinder. Airentrappedbetween the lower side of the piston 56 and the abutment 47passes through the vent 48.

Although the preceding is generally a preferred embodimerit,- analternative form of device may be used as shown in Figs. 4 and 5. Inthis form of device the arm 23- of the lever on the valve movableportion is omitted, to gether with allparts of the auxiliary cushioningdevice, but the remainder is like the power end of the device shown inPig. 1, and bears identical reference characters. In this case, however,the power cylinder 68 has a lower cushioning end. through which theshaft 61 passes,- and although, as shown, this is provided a fixed ratebleed, the variable bleed of Fig. 1 maybe used. The annular chamber 62has a vent opening 9' and communi cates with the interior of the clinder through the annular passage 63. The piston 64 mounted on. theshaft 61 has a lower tapered extension 65 surrounding the shaft inposition to enter, seal, and then to compress fluid entrapped in thepassage 63 and the annular chamber 62. as it is augmented bythecompressiorr of fluid between the lower face of the piston. and thelower cylinder closure 59 containing the passages 63 and 62. At the top,the cylinder is closed by the closure element 66 and has a port 67leading to a combined vent and power supply, "rust as is provided forcommunication with the vent from the annular chamber 62. A hand wheelcontrolled threaded shaft 68 passes through. the closure element 66, andcarries an internal. swivel head 70. A movable cylinder end wall deviceis provided hanging. upon the swivel head 70, and comprising the tubularexternally threaded member 71 having the fixed bleed radial vent 69, andengagedby the threaded cap 72 to hoid it to the head 7t At the lower endthe member 71 has an outwardly projecting flange 73 carrying a packingelement 74 held in place by the nut 75. The member 71 at the lower endis internally formed with a cylindrical axial valve seat 79 and the endof the piston shaft or red 61 extending beyend the piston 64 carries thesealing elongated plunger 76, The member 71 is large enough to receivethe upwardly advancing end of the plunger element and tocompress airtherein and to blce same through opening 69 to retard the motion of theadvancing piston. The power cylinder is so arranged that with themovable cylinder end at its upper position, a full power strokepredeterminedly cushioned at both ends of the stroke is provided. Whenit is desired to move one of the limits so as to shorten the stroke andstill to provide cushioning at both ends of the stroke, the shaft 63 isrotated, as by the hand wheel 78, as shown in Fig. 5, to move thecylinder end 73 and 74 down along the inside of cylinder 60. The powerstroke is then shortened with cushioning at both ends. While thecushioning. has been illustrated in these figures as a pre-set bleedrate with fixed ports, it will be understood, as noted, that if desiredthe bleed rate can be made adjustable as disclosed in Fig. l.

The simplicity andv efficiency of. the invention. will be obvious. H

Having thus described my invention, I claim:

1. A valve operator of variable stroke with cushioning means at each endof the variable stroke, comprising a 5 cylinder, a fixed head at one endof said cylinder, a piston slidable in the cylinder and defining withsaid fixed head and said cylinder a first pressure chamber, meanscommunicating with said first pressure chamber to energize same, apiston rod connected to the piston and slidable through said fixed head,complemental means on said piston and said fixed head for cushioning andthen stopping a stroke of said piston toward said fixed head, a fixedabutment mounted on the cylinder in spaced relation to said fixed head,a movable head of such cross sectional area as to be slidable in sealingcontact with the internal surface of said cylinder, said movable headdefining With said cylinder and said abutment a second pressure chamber,means communicating with said second pressure chamber for conductingfluid pressure through said movable head, means operable through theabutment for varying the position of the movable head axially of thecylinder, and complemental means on the piston and said movable head forcushioning and then stopping said piston in a stroke toward said movablehead.

2. A valve operator of variable stroke with cushioning means at each endof the variable stroke comprising a cylinder closed at one end by afirst head and at the other end by an abutment, an axially movable headof such cross sectional area as to be slidable in sealing contact withthe internal surface of said cylinder, a piston slidable in saidcylinder between said first head and said axially 6 movable head passagemeans for fluid pressure extending respectively through the respectivefirst head and through said abutment and said movable head tocommunication with the interior of said cylinder on respect velyopposite sides of said piston, a piston rod connected to said piston andslidable in the said first head, complemental dashpot means on saidpiston and said first head for cushioning preliminary to stopping astroke of said piston toward said first head, complemental da'shpotmeans on said piston and said movable head for cushioning preliminary tostopping a stroke of said piston toward said movable head, and meansoperating through said abutment for positioning said movable head tovary the axial length of a piston chamber defined between the respectiveheads and thus to vary the total complete stroke of said piston.

References Cited in the file of this patent UNITED STATES PATENTS531,792 Forslund Jan. 1, 1895 1,226,673 Kane May 22, 1917 1,445,615Ferris Feb. 13, 1923 1,558,590 Carlson Oct. 27, 1925 1,686,109 StuckeyOct. 2, 1928 1,707,111 Brady Mar. 26, 1929 1,931,489 During Oct. 24,1933 2,223,792 Muir Dec. 3, 1940

